General visual improvement on the calendar + Font size selection + selection box around the day clicked.

Fixes #1145

public/locales/en/modules/calendar.json

@@ -15,6 +15,9 @@
       },
       "hideWeekDays": {
         "label": "Hide week days"
+      },
+      "fontSize": {
+        "label": "Font Size"
       }
     }
   }